Air-cooled internal combustion engine



June 7, 1938. H. TOWNS AIR COOLED INTERNAL COMBUSTION ENGINE Filed Sept.21, 193'? 2 Shets-Sheet 1 June 7, 1938. H. L. TOWNS AIR COOLED INTERNALCOMBUSTION ENGINE Filed Sept. 21, 1957 2 Sheets-Sheet 2 Patented June 7,1938 UNITED STATES AIR-COOLED COMBUSTION ENGINE Herbert signpr Coventry,England Langley Towns, Coventry, to Armstrong Siddeley Motors Limited,

England, as-

Applicat ion September 21, 1937, Serial No. 164,992 In Great BritainAugust 9, 1937 3 Claims. .(Cl. 123-55) This invention relates toair-cooled internal combustion engines, particularly for use inaircraft, of the kind having X rowsmf'cylinders arranged radially in acircle and spaced angularly from one anothe ,.-;ach row comprising Y yind rs wh re and a e iheth ereate th n w and a y nd of a h rowhe easstiated with one of the throwsof a-gra nkshaft having as many throws asthere are cylinders in a row, i. e., having Y throws,

In the case of many such engines it is possible to arrange for equalfiring intervals for all the cylinders when the cylinders of each roware in a longitudinal plane ,and the crankshaft is 115 a symmetricalone-i. e.,rn the case of a 3-throw crankshaft, the throws are angularlyspacedfrqin n anoth Thi v is iereraniple, the ease .e a en n ha n fiverqw 9 t ree @1 inders. In the case of an engine havinga b p y ind rs i his e xe t ni isible nt 3 .0. n whe th number X .o row is xa t d s l i tt numbe Y) o y iner i rrow, .or wh r t numbe KY Q c ingene i a r w isact di s bl n o th 1 1 h r :X) 9 ws o ammean n ne ha in ni e w e th ecyln e when .ns ne a crankha t with eq l p e thro the .u n pract t :w lildeto a ran e for the .eylind rs, as oc ated w th on th ew to ,b sta er dwith res ec to those associated with another throw.

New. a co in t th p ese inv n i n. t linders .Q each r ar ar an ed in alon itudina la an he c an shaft i ne a ymm trica n but the thrqws are anl rl s aced i regula y wi h r t to the anti-he sea o provide o equa i tval of irin o all the ylinders In t is W y .i s n sible t u d a largecompa t a ro d e in in a Ve satisfactory manner. I

Th nvention i parti ul r ap li able -tean engine where th n e .qfylihdlh 1 row, is three or some ,other ,odd number, and in this eventthe angular spacing ofpne throw from another is L" XY provided that thevalue is not or a multiple thereof. 7

The arrangement is preferably such; where Y is three, thatthe front andrear throwsare angu iarly. 'pa ed q a y r jt c ntre thr -'f I n theaccompanying drawings:-

the angular spacingsbf the three throws and of front and rear balanceweights for one system of balance weights?" Figures 3 and 4 are diagramscorresponding to w H Y axial view of the engine taken mainlyoiithli'rie'V-'V of Figure 6 and showing by dotted lines the two masterconnecting rods associated ,jwith the other two crankllliQWi nd Y"F'igur 6"is a'longitudinal section through the three master connectingrods taken niafinly'on the line VIVI of Figure 5.

In all the figures, the arrow represents the direction of crankshaftrotation. In Figure 3 the front throw is shownto the left of the centrethrow, and in Figure 4 .to the right thereof.

In all the figures, A represents the front throw, B the centre throw and.C the Irear throw. D represents and is numerically proportional ,to asingle front balance weight and E a single rear balance .w'eig'ht. istheradius of the throws, G the radius of the centre of mass of the balanceweights. H1is .the axial distance between the centres of two adjacent"throws, J the axial distance between the centre of mass of eitherbalance weight and thecentre of the adjacent throw. K is the anglebetween the'front throw and the centrthioyv, L the anglebetween the rearthrow and thecentre throw, -M the angle between the centre of mass of,the front ba..ance weight and the centre ,throw, and N the anglebetween the centre of mass of the rear .balanceweight and the centrethrow.

Theangles K .and Lars (i. e., l3? ZOZwhen th nnmhe n Y9W$,9 .Q inders,is 9. and Y, the niumberiof cylinders in a row, is 3) or a, multipl ethereof but such multiple shall nottbe I or a, n ultiple thereof.

,If thefiring' orderis known then the angles K'and Lare' known. Forexample (denoting the cylinders inorie row by-the reference I, those inthelnext row by the reference 2, and so on, the c ylindersjn thelast-row=being denoted-by the reference ,9), ii the firing order is 1A,5B, 10, 3A,

7B, 30, 5A, 9B, 56, K is 133 20' (ten L is 173 20' (thirteen times 1320').

714,213, 7C, etc.,

times 13 20) and the angle The actual lowing four iormulaezt V v (1) Ecos N+D cos ll1=cos (180K)+cos (180L)1 2 D sin M-E sin N=sin (180K)sinisc-L) (4) E sin N+D sin M J +H{ is; 52 3 Assuming that the solution ofthese equations is The front balance mass is actually F D. multiplied bythe crank pin mass and the rear balance mass F multiplied by the crankpin mass.

For other firing orders other values will be chosen forthe anglesK andL.

In carrying out the invention, however, it is preferable that the frontand rear throws should be equally spaced from the centre throw, i. e.,that the angles K and L should be equal. In this case angle Mequalsangle N, and D equals E.

In thefollowing table ILgiVe a. complete range of values for the systemsshown by Figures 3 and 4, assuming that the value of M=N D=E Fig. Firingorder 3 1A, 2B, 30, 3A, 4B, 50, etc.

4 1A, 1C, 23, 3A,

30, 413, etc.

50, 513, etc.

4 1A, 1B, 1C, 3B, 30, etc.

3 1A, 3B, 50, 5B, 70, etc.

4 1A, 80, 1B, 10, 313, etc.

3 1A, 50, 413, 3A, JQ, 6B, etc.

4 1A, 60, 9B, 80, 2B, etc.

3 1A, 70, 5B, 90, 73, etc.

4 1A, 8B, 60, 1B, 8C, etc.

a 1A, 5B, 90, 3A,

7B,20,etc.

then the angle" It will b obvious that more than two balance masses canbe used if desired. It should also be noted that K=L is never equal to(i. e., or to obtained for values of K=L or 3(13 20') which equals 360"3?? or 6 (13 20'), which equals 2 n five rows of three each) for whichthe normal I.

practice of providing equal intervals of firing ofall the cylinderswould be to arrange the cylinders of the rows in longitudinal planes andto use K=L M=N D'=E Fig. Firing order 3 1A, 90, 6B, 3A. 20, 813, etc.

11 (13 20')=l46 40' 53 20 -56 5 4 1A, 713,40, 3A, 9B, 60, etc.

3 1A, 6B, 20, 3A, 8B, 40, etc. 13 (13 20)=173 20 10 54 -502 A. t Y 4 1A,20," 7B, 3A, 10

" 40, 913, etc.

or a multiple thereofi. e., even firing cannot be a symmetricalcrankshaft, with Y equally-spaced throws.

What I claim as my invention and desire to secure by Letters Patent ofthe United States is 1. An air-cooled internal-combustion engine havinga Y-throw crankshaft, and 'X rows of cylinders arranged radially in acircle and spaced angularly from one another; each row comprising Ycylinders arranged with their main axes in a longitudinal plane andassociated, respectively, with the throws of the crankshaft, where X"and Y are both greater than 2 and where Y is an odd number,characterized in that the crankshaft is an unsymmetrical one having itsthrows 'angularlyspaced with respect to one another by angles which areXY- or any multiple thereof, provided that the value thereof is not J, V

36g; X I ora multiple thereo 1 p V p 2. An air-cooledinternal-combustion engine. having a 3-throw crankshaft, and X rows ofcylinders (X being greater than 2) arranged radially in a circle andspaced angula'rly from one another, each row comprising 3 cylindersarranged with their main axes in a longitudinal plane and associated,respectively, with the throws oi. the crankshaft, characterized in that-the crankshaft is an unsymmetrical one having its front and rear throwsangularly spaced equally from the third throw by angles which are or anymultiple thereof, provided that the value thereof is not or a multiplethereof.

3. An air-cooled internal-combustion engine having a 3-throw crankshaft,and 9 rows of cyl- 3 (13 20') or any multiple 10

